The invention relates to vehicle seats and particularly to a fore and aft adjustment and isolation assembly of the general type disclosed in copending application, Ser. No. 149,206 filed May 12, 1980 and assigned to a common assignee.
Since vehicles, particularly large trucks, must be provided with suspensions which are capable of handling very heavy loads, they cannot offer the smooth ride of a passanger car. In order to protect the driver from fatigue and the great discomfort induced by vehicle vibrations, it is quite common to provide seat suspension systems incorporating mechanical or fluid springs. The springs isolate the driver from the vertical vibrations, but consume a considerable amount of space under the seat. This is especially true in the case of air spring suspensions which are greatly preferred over mechanical suspensions due to the fact that they have a constant natural frequency and can be automatically adjusted to the weight of the occupant. Most seats have slide rails which permit a fore and aft position adjustment and many have a fore and aft isolation feature which isolates the occupant from fore and aft and pitching vibrations and is typically located under the center of the seat pan and above the suspension. When a seat is provided with all of the aforementioned features, it must have its seat pan a considerable distance above the floor in order to accommodate them and becomes too high to be used in certain vehicles which have a relatively limited space between the floor and ceiling. Accordingly, it would appear desirable to have a seat wherein the fore and aft position adjustment and the fore and aft isolation mechanism would not require any more vertical height under the seat.